1. Field of the Invention
The present invention relates to a specimen mount for use in secondary ion mass spectrometry and other sensitive particle beam analysis methods, and a method for operating such a specimen mount.
2. Description of the Prior Art
Higher and higher demands are being made on the capability of secondary ion mass spectrometry (SIMS), particularly in the field of semiconductor development. For many applications, for example, the concentration span which can be registered in a depth profile ("dynamic range") should be expanded from above 10.sup.21 atoms/cm.sup.3 to below 10.sup.14 atoms/cm.sup.3, and the documentation boundaries for dopant-active elements of interest, for example boron and antimony, should be lowered as far as possible.
A problem in the art is the generation of disruptive signals which result from the environment of the sputter crater which is generated during secondary ion mass spectrometry and other particle beam analysis methods. Particularly in secondary ion mass spectrometry, current performance limits with respect to the above two criteria are defined by disruptive scatter components deriving from the rim of the sputter crater which arises during measurement and from the environment thereof. It is extremely difficult to reduce such disruptive signal contributions by further processing measures, however, a considerable improvement can be achieved without significant outlay by suitable specimen preparation.
A specimen mount for secondary ion mass spectrometry is described in European patent application EP No. 0 070 351 A wherein the specimen to be analyzed is bombarded with an ion or particle beam, and the specimen is completely disposed, without surrounding environment, in the inside of the region on which the ion or particle beam is incident. Disruptive influences of the crater rim and surrounding environment are largely avoided by use of this specimen mount.